Onosma bracteatum Wall and Commiphora stocksiana Engl extracts generate oxidative stress in Brassica napus: An allelopathic perspective

Abstract The use of synthetic chemicals as herbicides for crop protection is a big threat due to toxicity, non-degradability, and negative impact on environment. Onosma bracteatum leaves and flowers, and Commiphora stocksiana Engl bark ethanolic extracts are evaluated for allelopathic potential against Brassica napus, a model plant. Complete allelopathic tendency was depicted by crude extract of O. bracteatum leaves and partial trend by flower and C. stocksiana extracts. B. napus seed germination efficiency and plant architecture is adversely influenced by the presence of plants extracts. The antioxidative analysis of Brassica plants depicts that extracts in the growth environment produces oxidative stress that eventually increased free radical scavenging activity, total antioxidative potential, and reducing power capability. Though Brassica plants produced phenolics and flavonoids to combat the oxidative stress but at insufficient concentration. Based on the findings, it can be concluded that the plants extracts produce oxidative stress to the seedlings and plants that eventually results in toxicity and allelopathic effect. Furthermore O. bracteatum can be a good candidate for natural herbicide either in form of extracts or the allelopathic compounds isolated from this plant species, which can be used as replacement of expensive and harmful synthetic herbicide.